The communications and radar industries have interest in reactive-type broadband microwave dividers and combiners. Even though not all ports are RF matched, as compared to the Wilkinson power divider/combiner (see Ernest J. Wilkinson, “An N-way hybrid power divider,” IRE Trans. on Microwave Theory and Techniques, Jan., 1960, pp. 116-118), the reactive-type mechanical and electrical ruggedness is an advantage for high-power combiner applications. This assumes that the sources to be combined are isolator-protected and of equal frequency, amplitude and phase. Another combiner application is improving the signal-to-noise ratio of faint microwave communication signals using an antenna dish array connected to the reactive power combiner using phase length-matched cables. The signal from each dish antenna sees an excellent “hot RF match” into each of the N combining ports of the reactive power combiner and is therefore efficiently power combined with the other N−1 antenna signals having equal frequency, amplitude, and phase. However, the cable- and antenna-generated thermal noise signal into each port of the N-way power combiner (with uncorrelated phase, frequency and amplitude) sees an effective “cold RF match” and is thus poorly power combined. The signal-to-noise ratio improves for large values of the number of combiner ports N. Still another application is for one of two reactive N-way power dividers to provide a quantity N signals of equal phase, amplitude and frequency as inputs to a set of N broadband amplifiers each with a noise figure X db/MHz. A second high-power N-way reactive power combiner is used to combine the N amplified signals with the benefit of improving the overall total noise figure by several dB.
An example of a reactive combiner/divider is described in U.S. Pat. No. 8,508,313 to Aster, incorporated herein by reference. Broadband operation is achieved using two or more stages of multiconductor transmission line (MTL) power divider modules. An 8-way reactive power divider/combiner 200 of this type is shown in FIGS. 4 and 5 of application Ser. No. 15/043,570. Described as a power divider, microwave input power enters coax port 201, which feeds a two-way MTL divider 202. Input power on the main center conductor 206 (FIG. 6a, Section a1-a1) is equally divided onto two satellite conductors 207 which in turn each feed quarter-wave transmission lines housed in module 203 (FIG. 4). Each of these quarter-wave lines feeds a center conductor 208 (FIG. 6b, Section a2-a2) in its respective four-way MTL divider module 204, power being equally divided onto satellite conductors 209 which in turn feed output coax connectors 205. This may also be described as a two-stage MTL power divider where the first stage two-way divider (Stage B, FIG. 7) feeds a second stage (Stage A, FIG. 7) consisting of two 4-way MTL power dividers, for a total of eight outputs 205 of equally divided power. This two-stage divider network is described electrically in FIG. 7 as a shorted shunt stub ladder filter circuit with a source admittance YS(B) and a load admittance NS(B) NS(A) YL(A). The first-stage (Stage B) quarter-wave shorted shunt stub transmission line characteristic admittances have values Y10(B) and NS(B) Y20(B), respectively, which are separated by a quarter-wave main line with characteristic admittance value NS(B) Y12(B). Here the number of satellite conductors NS(B)=2, NS(A)=4 and Y12(B) is the value of the row 1, column 2 element of the 3×3 characteristic admittance matrix Y(B) for the two-way MTL divider (Section a1-a1, FIG. 6). Also, Y10(B)=Y11(B)+NS(B) Y12(B) and Y20(B)=Y22(B)+Y12(B)+Y23(B). Each quarter-wave transmission line within housing 203 (FIG. 4) has characteristic admittance YT and is represented in the equivalent circuit FIG. 7 as a quarter-wave main transmission line with characteristic admittance NS(B) YT. The second stage (Stage A) quarter-wave shorted shunt stub transmission line characteristic admittances have values NS(B) Y10(A) and NS(B) NS(A) Y20(A), respectively, which are separated by a quarter-wave main line with characteristic admittance NS(B) NS(A) Y12(A). Here Y12(A) is the value of the row 1, column 2 element of the 5×5 characteristic admittance matrix Y(A) for one of the two identical four-way MTL divider modules 204 (FIG. 4) with cross-section a2-a2 in FIG. 6b. A plot of scattering parameters for an octave bandwidth two-stage eight-way divider is shown in FIG. 4c of U.S. Pat. No. 8,508,313. Due to its complexity, the two-stage, three MTL module power divider/combiner as shown in FIGS. 4 and 5 is expensive to fabricate.